The present invention relates to a dilator for a balloon catheter, more particular to a dilator for enlarging a constricted portion of a blood vessel for the balloon catheter.
A balloon dilation catheter is introduced into a body of a patient to enlarge a constricted portion of a blood vessel and Other body cavities. In a conventional procedure, firstly, a guide wire is introduced into a blood vessel and manipulated to pass the constricted portion. Then, the balloon dilation catheter is inserted into the blood vessel along the guide wire. The balloon catheter is pushed into and positioned in the constricted portion, and the balloon is inflated to enlarge the constricted portion of the blood vessel.
The guide wire is a very small flexible wire with a coiled tip to protect a wall of the blood vessel. The guide wire is small enough to pass the constricted portion of the blood vessel, but in many occasions, the constricted portion is too small for the balloon catheter to pass. In this case, the operation by the balloon catheter is quitted and an alternative treatment is performed for the patient, .because the constricted portion of the blood vessel can not be enlarged by the balloon.
Many attempts have been made to make a balloon catheter with a small profile at the distal or front end of the catheter. Currently, the smallest profile of the balloon catheter available on the market is still about twice the diameter of the guide wire , i.e. 0.28 inches.
There is an inherent limitation to make the balloon profile smaller since the balloon catheter must have a folded balloon and inflation/deflation tube at the balloon section, and a shaft. Also, the balloon is folded at the time of the insertion, but the folded balloon tends to loosen during the manipulation of the balloon catheter before reaching the constricted portion. This will add the difficulties to enter the balloon catheter into the constricted portion.
Accordingly, an object of the invention is to provide a dilator for a balloon catheter in order to enlarge a constricted portion of a blood vessel to allow the dilator to enter into the constricted portion prior to the insertion of the balloon catheter.
Another object of the invention is to provide a dilator as stated above, which can be exchanged with the balloon catheter easily without a trouble.
A further object of the invention is to provide a dilator as stated above, which can be made at a low cost.
Further objects and advantages of the invention will be apparent from the following description of the invention.